Small internal combustion engines are commonly started by rope starters using rope receiving pulleys automatically rewound by a coil spring. Such recoil starters usually employ dogs mounted upon the rope pulley which extend to engage an engine flywheel mounted cranking cup when the pulley is rotated in a cranking direction, and rotation of the pulley in a recoil direction automatically retracts the driving dogs to an inoperative position. Recoil starters of the aforementioned type are typified by the assignee's U.S. Pat. Nos. 2,926,648; 3,375,814; 3,782,355 and 3,871,350. The assignee's U.S. Pat. Nos. 3,081,760; 3,099,255 and 3,267,922 are rotated by spring power and inertia, rather than a rope and recoil spring, but utilize engine cup dog engaging elements similar to those employed in rope type recoil starters.
As apparent from the above patents, the rotating member, either a rope pulley or inertia member, utilizes dogs and an operator to selectively engage the engine cranking cup, and while the dog operator often includes a friction brake, the heavy engine vibration to which starters are subjected will often cause the dog operator or actuator to slowly move in a direction permitting the dogs to extend and engage the rotating engine cranking component. Such inadvertent dog extension is undesirable as the cranking dogs, or engine cup, may be damaged, objectionable noises are produced, and the dogs are subjected to abnormal wear. While various techniques have been utilized to prevent such inadvertent dog extension, such as a spring biased dog actuator and interfering surfaces defined upon the actuator and dog, such innovations have not solved the problem.
Also, known recoil starters have been subject to problems retaining the rope within the pulley groove during recoiling, and further, as recoil starters are usually mounted adjacent the engine flywheel, the cooling air flow produced by the flywheel vanes is often restricted due to the presence of the starter mass and, previously, starter construction has not overcome this problem.
It is an object of the invention to provide a recoil starter for internal combustion engines wherein inadvertent starter dog extension is prevented.
Another object of the invention is to provide a recoil starter for internal combustion engines wherein a concise starter construction is achieved, inadvertent dog extension is prevented and positive means are employed to retain the dog operator in the dog retract position.
A further object of the invention is to provide a recoil starter for internal combustion engines wherein the starter uses a dog operator rotatable about the rope pulley axis, and a spring biased detent is employed to maintain the dog operator in the dog retracted position.
Yet another object of the invention is to provide a recoil starter for internal combustion engines wherein the starter recoil spring is located within a keeper, and the spring keeper includes a skirt extension circumscribing a majority of the rope pulley groove to maintain the rope within the groove during the recoiling.
Yet another object of the invention is to provide a recoil starter of concise configuration wherein the starter components are of a configuration which aids in the flow of cooling air into the engine past the starter.
An additional object of the invention is to provide a recoil starter utilizing a rope pulley having a configuration which cooperates with the engine cranking cup to aid in maintaining a proper relationship between the pulley and cup.
In the practice of the invention, a rope pulley is rotatably mounted upon a housing which is attached to a small internal combustion engine. The starter housing includes louvers or vents through which cooling air may pass as circulated by the engine flywheel, an engine cranking cup being attached to the flywheel. The rope pulley is concentric to the engine flywheel and includes a rope groove in which the starter rope is received. A spiral recoil spring is interposed between the pulley and housing for rewinding the pulley after cranking the engine, and the recoil spring is mounted within a keeper or housing having a skirt extension extending over the rope circumference to maintain the rope within the pulley groove.
Clutch drive dogs are pivotally mounted upon the rope pulley hub and are maintained within recesses by a platelike operator coaxially mounted upon the pulley and frictionally rotatable thereto as controlled by a friction brake. Actuating surfaces defined upon the operator cooperate with the dogs wherein relative movement between the pulley and operator causes the dogs to extend during pulley cranking rotation for engagement with the engine drive cup, and retract during rope pulley rewind or recoiling.
Cam detent engaging surfaces are defined upon the dog operator, and the dogs, themselves, have cam surfaces defined thereon for engaging with the operator surfaces and coil springs imposing an axial force upon the dogs biases the dogs into engagement with the operator, wherein the dogs, themselves, function as detents to prevent inadvertent rotation of the operator due to engine vibration. In this manner, relative movement of the pulley and dog operator is prevented during engine running, and yet the arrangement for restraining the operator against rotation imposes no additional cranking resistance upon the user.
The configuration of the starter, and particularly the rope pulley, closest to the engine flywheel and driving cup, includes surfaces generally converging toward the flywheel which aids in the flow of cooling air through the starter housing into the engine.
From the above, it will be appreciated that the desired objects have been achieved by the subject matter of the invention.